The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling-down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling-down has also increased the complexity of processing and manufacturing ICs.
For example, there is a growing need to perform higher-resolution lithography processes. One lithography technique is extreme ultraviolet lithography (EUVL). The EUVL technique employs scanners that use light in the extreme ultraviolet (EUV) region, having a wavelength of about 1-10 nm. Some EUV scanners provide 4 times reduction projection printing, similar to some optical scanners, except that the EUV scanners use reflective rather than refractive optics, i.e., mirrors instead of lenses.
EUV radiation is absorbed in virtually all transmissive materials, including gases and glasses. To minimize unwanted absorption and to avoid EUV intensity loss, EUV lithography patterning is maintained in a vacuum environment. Therefore, the semiconductor wafer stays in a load lock chamber and will not be transferred to the EUV exposure chamber until vacuum pressure is created in the load lock chamber.
Although existing methods and devices for creating the vacuum pressure in the load lock chamber have been adequate for their intended purposes, they have not been entirely satisfactory in all respects. Consequently, it would be desirable to provide a solution to more efficiently create a reduced pressure or high vacuum in a load lock chamber.